Several underlying systemic problems at the strategic level and at the program level continue to contribute to poor weapon systems acquisition. The total acquisition cost of DOD's 2007 portfolio of major programs has grown by 2(3 percent over initial estimates. At the strategic level, DOD does not prioritize weapon system investments, and its processes for matching warfighter needs with resources are fragmented and broken. DOD largely continues to define warfighting needs and make investment decisions on a service-by-service basis and assesses these requirements and their funding implications under separate decision-making processes. Invariably, DOD and the Congress end up continually shifting funds to and from programs undermining well- performing programs to pay for poorly perform ones. At the program level, weapon system programs are initiated without sufficient knowledge about requirements, technology, and design maturity. Instead, managers rely on assumptions that are consistently too optimistic, exposing programs to significant and unnecessary risks and ultimately cost growth and schedule delays. In December 2008, DOD revised its guidance to improve its acquisition of major weapon systems, consistent with recommendations GAO has made. We have previously raised concerns, however, with DOD's implementation of guidance on weapon systems acquisition.